GENERAL MICROBIOLOGY - T.P. Pyrog - 2004

6. MICROBIAL GROWTH

6.3. MICROBIAL NUTRITION

6.3.3. Nutritional Types (Trophies)

The Classification of microbial Nutritional types is based on the terminology proposed in 1946 at a symposium in Cold Spring Harbor. The following nutritional types (trophic categories) are distinguished:

1) regarding the energy source (chemo — chemical, photo — light);

2) regarding the electron donor (organo — Organic compounds, litho — Inorganic Compounds). Such inorganic electron Donors include H₂, NH₃, H₂S, S, CO, Fe²⁺, etc.;

3) regarding the carbon source (auto — carbon dioxide, hetero — organic compounds).

Combinations of all these terms make it possible to describe most nutritional types (Table 6.4). All of them correspond to actually existing microorganisms (Table 6.5). The most extensively studied nutritional type is organoheterotrophy. In this case, a carbon compound is utilized by the microorganism as the sole source of carbon, energy, and electrons.

Table 3.4.

Characteristics of bacterial nutritional types

Energy source	Electron donor	Carbon source	Nutritional type
Redox reactions	Inorganic compounds	СО₂	Chemolithoautotrophy
Same	Same	Organic compounds	Chemolithoheterotrophy
-	Organic compounds	СО₂	Chemoorganoautotrophy
	Same	Organic compounds	Chemoorganoheterotrophy
Light -	Inorganic compounds	СО₂	Photolithoautotrophy
	Same	Organic compounds	Photolithoheterotrophy
-	Organic compounds	СО₂	Photoorganoautotrophy
-	Same	Organic compounds	Photoorganoheterotrophy

Table 6.5.

Nutritional types of various physiological groups of microorganisms

	Growth substrates			Nutritional type
Microorganisms	Energy source	Electron donor	Carbon source	Nutritional type
Cyanobacteria, Purple and green Algae	Light	H₂O, H₂S, H₂, SO₃^2-, S⁰	СО₂	Photolithoautotrophy
Purple and green Bacteria	-	H₂S, S₂O₃^2-, H₂	Organic compounds	Photolithoheterotrophy
Purple sulfur bacteria	-	Organic compounds	СО₂	Photoorganoautotrophy
Purple bacteria	-	Same	Organic compounds	Photoorganoheterotrophy
Hydrogen, methanogenic, and acetogenic bacteria	H₂	H₂	СО₂	Chemolithoautotrophy
Nitrifying bacteria	NH₃	NH₃	CO₂	Same
Iron bacteria	Fe²⁺	Fe²⁺	CO₂	-
Desulfovibrio desulfuricans	H₂	H₂	Organic compounds	Chemolithoheterotrophy
Utilize only organic substrates	Organic compounds	Organic compounds	Organic compounds	Chemoorganoheterotrophy

Last update: 13/08/2026

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